Fluid storage system



Oct. 22, v1935. w, G, LAIRD 2,018,270

FLUID- STORAGE SYSTEM Filed June 15, 1931 2 Sheets-Sheet l INVENTOR J0l. r waaura. Laird ATTORNEY Oct. 22, 1935. w. G. LAIRD 2,018,270

FLUID STORAGE SYSTEM Filed June 1s, 1951 2' Sheets-Sheet 2 Wilbur 6.Laird ATTORNEY Patented on. 22, 1935 UNITED STATES PATENT OFFICE STQBAGESYSTEM Wilbur G. Laird, Pleasantvllle, N. 'Y., asslgnor to DohertyResearch Company, New York, N. Y., a corporation-of Delaware ApplicationJune 15, 1931, Serial N... 544,48

8 Claim.

I When direct solar heat raises the temperature of liquid petroleum. andthe contents of the vapor space within a sealed storage tank, thepressure within the tank may rise rapidly due to the evolution" ofdissolved gases and evaporation of the volatile fractions of the oil andthe expansion of the gaseous contents of the vapor space above theliquid. The pressure'within an oil storage tank, thus exposed to solarevaporation and expansion, if not-immediately corrected, as by releasingvapors to the atmosphere, may attain such proportions that the tank mayburst. Moreover under conditions where. the temperature of thesurrounding atmosphere drops rapidly, the pressure within a sealedstorage tank may drop below atmospheric due to the condensation andcontraction of vapors and gases. In such a case thepressure withinthetank may drop to the point where the walls or the roof thereof willcollapse.

It has been proposed to overcome these difliculties and at the same timeprevent vapor loss I and reduce danger from fires as a result-of admetalwhich will withstand only very low presmission of air into the tank,byconnecting the vapor space of a sealed oil storage tank in closedcircuit with a variable volume gasholder, so that the pressure withinthe tank may be controlled by free breathing or vapor flow between thetank and the gasholder. However it is often impracticable to provide*bipes connecting the storage tank and gasholder of sufliclent capacityto allow the rapid breathing which would sometimes be required toprevent development of abnormal sure differentials between thesurrounding atmosphere and" the inside of the tank. This type of tankroof maynot always have suflicient in- I invention;

herent strength to withstand the pressure. amounting to several inchesof water, which is imposed by a gasholder lift on a closed vapor storagesystem such as described in my U. S.

Patent 1,794,383. The strongest section of such 5 tanks is at theirbottom curb, such curb being designed to withstand the hydrostaticpressure of the body of oil stored.

One object of the present invention is to provide a system ofreinforcement for the common 1 type of cone-roofed oil storage tankwhereby a large tank may be strengthened to withstandpressurevdiflerentlals up to several ounces between its interior and theoutside atmosphere.

A feature of the tank reinforcement provided 15 by the present inventionis that it is simple in design and economical to install, enabling theuse of previously erected cone-roofed storage tanks ina vaporconservation system such as that described in my said Patent No.1,794,383, II

at a fraction of the cost that would be involved in rebuilding the roofin stronger form or in replacing such tanks with new tanks of suitablestrength and storage capacity.

Another object of the present invention is to ll provide an improvedtype of safety valve adaptable to a closed liquid storage system tocorrect any abnormal pressures developed within the system.

Other objects and advantages of the invention 30 Q will be apparent fromthe following detailed description, taken with the accompanyingdrawings, in which:

Fig. 1 is a view in diagrammatic vertical section of'a liquid storagesystem embodying the improvements forming the subject of the presentFigr 2 is an enlarged diagrammatic top plan view of partof the roof ofthe oil storage tank shown in Fig. 1,-parts being brokenaway to show theconstruction of underlying parts;

Fig. dis a detailed-view illustrating one way of assembling the rodspreferably used according to the present invention for reinforcing theoil storage tank Fig. 4 is a vertical sectional view of the preferredsafety valve element of the improved oil storage system, parts being inelevation:

Fig. 5 is a top plan view of the safety valve shown in Fig, 4; and 50"Fig. 6 is an enlarged vertical sectional view of a portion of the valveactuating mechanism shown in Fig. 4, illustrating the operation of. themechanism due to excessive pressure within the system I Referring to thedrawings (Fig. 1), the liquid to be stored is placed in a storage tankI6 having cylindrical walls I2'and a conical roof I6 tightly sealedagainst the escape o; gases and vapors. The roof I4 .02 the storage isreinforced by channel beams I6 which are preferably placed on top of theroof in radially extending spaced relationship and which act to maintainthe roof rigid under interiortank pressures that would tend to bucklethe ordinary type of unreinforced conical roof.

Attached toeach channel I6 at the approximate midpoint thereof, arebrackets I6 (Fig. 3) which together with the channel beam I6 support aplate 26. An adjustable eye-bolt 22 extends through the plate 26 androof I4, and is pivotallyconnected to the approximate midpoint of apivotal pin plate 24 located within the tank I6. A tension reinforcingmember in the form of an eye bolt or rod 26 is pivotally connected toplate 24 and extends to a bracket 26 attached to a plate 66 located atthe bottom curb 62 of the tank I6. with which the rod 26 is inadjustable engagement. From the other end of the plate 24 a pivotallyconnected rod 64 extends and is in adjustable engagement with a bracket.66 attached to a center plate 66. Although the tank reinforced accordingto the present invention may not have a central roof support, the centerplate 66 may-have a central opening as .at 46 and may be separable so asto encircle a center post, if it is desired to; apply the tankreinforcement to a storage tank which is equipped with a center roofsupport.

The system of reinforcement as described in connection with the tying ofthe roof by reinforcing members to the bottom curb of the tank, may besimilarly applied to any number of a pluralityof channel beams I6. eachpivotal J plate 24 having reinforcing rod connections extending tothebottom curb of the tank and to the centrally located plate 66 withinthe tank. The center plate 66 obviates the necessity of the horizontal,tie rods crossing at a common point in the center of the tank.

Such a tank reinforcing system is completely adjustable by means of thenuts-on the rods 22, 26 and 34. By means of these nuts the entirereinforcing system may be firmly and rapidly installed. The eye bolts 22may be packed, or welded to the roof, at the point where theypasstherethrough, to prevent leakage, and the roof may thus bepermanently'reinforced so as to pletely illustrated withstand pressuredifferentials up to several ounces between the interior of alarge tankand the outside atmosphere.

The vapor space of the storage tank I6, rein-. forced as abovedescribed, is connected by means of a vapor conduit 42 to a safety valve44 suitably mounted upon ;the roof of the tank I6 by. means of levelingbrackets, and thence-by means of a vapor conduit 46 to the bell of avariable volume gasholder 46 (Fig. 1). While but one oil storage tank isshown as being connected to the bell of the gasholder 46, it is obviousthat a series of interconnected oil storage tanks may be connected tothe gasholder 46 in a system such as described in my Patent No.1,794,383. 1

The safety valve 44, the application of which according to the oilstorage system of the present invention is shown in Fig. his more cominFlgs.4, 5, and 6 of the drawings.

The valve 44 comprises a chamber "having a vapor inlet 62 from pipe 62,a mmoutlet pipe 64 formed as an extension of the vapor conduit 46, and anormally closed outlet pipe 66 leading to the atmosphere throughopenings 66 which are situated beneath, and protected by, afrusto-conicalv cover 66. Within the chamber 66 is a pair of buckets 62and "64, each having knife edge trunnions 16 on opposite sides of itsrim with which the ends of beams 66 and 66 pivotally engage. Thebeams-66 and 66 are pivotaily mounted at their midpoints upon a shaft 10I2 which is in turn pivotally supported by brackets. I3 afllxed'toopposite walls of chamber. 66. The buckets 62 and 64 are mounted inunbalanced weight relationship to each other. The beam end having thebucket 62 and its restraining rod is the heavier and is normally held inan elevated position in sealing relationship with the outlet pipe 66.The bucket 64 is shown in its'normally depressed position, allowing freeflow of vapor iiireiigh the outlet pipe in '(Fig. 5). When the 2 0bucket 62 is lowered, there is open communicae-e tion between chamber 66and the atmosphere through the pipe 56. Bodies of liquid I4 and I6,which may be water in the summer and oilin the winter, are maintained inthe buckets 62 and 64, respectively, so as to act as sealing liquid whenthe buckets 62 and 64 are in sealing engagement with the respectivepipes 66 and 64. Above the chamber 66 is located a diaphragm chamber 16which contains a common form of so movable diaphragm 66 dividing thechamber I6 into two compartments 62 and 64. The compartment 82communicates with the chamber 66 through a conduit 66 and 66, and thecompartmeat 84 communicates with the atmosphere as through port 66. A-branch is provided from the conduit 66 and is valved at 62 to permitattaching a gauge to determine the pressure within the system. A valveis'providedat 64 in conduit 66 for the purpose of closing off communica-4o 7 tion between chambers 66 and 16, should discontinuance of theoperation of the safety valve be desired.

i The diaphragm 66 operates the rod 66. which moves upwardly ordownwardly as the pressure within the tank- I6 and chamber 66 changes.The rod 66 is slidably attached to the double bellcrank 66, the T-endsof whichare in turn slidably attached to the slotted ends of bars I66and I62. The bars I66 and I62 are pivotally secured to by pins to alatch I which is inturn pivotally connected to a bracket I66 extendingupwardly from the cover 66. The double bell-crank 664s fulcrumed by, andattached to, a shaft I66 which isjournaled in brackets 6 extendingmar-div 66 from the diaphragm chamber. I6.

' On the shaft I66 a member H2 is mounted so as to actuate with theshaft I66 in response to movements of the diaphragm 66. Uponupwarddiaphragm movement the member I I2-comes into contact with andraises the lever arm II4, which is loosely pivoted upon the shaft I66. AoounterweightJ I6 is adjustably mounted on the free end of lever arm II4 toj'counteract the pressure under the diaphragm so until apre-determined or I pressure is reached. The lever arm III, under.

normal pressure conditions within the system, rests upon a rest bracketIII. Similarly on another part of the'shaft I66 is mounted a'member I26whichactuates with the 70 shaft I66 in response to movements of the diaphragm 66 caused by pressurechanges within the system. With downwarddiaphragm movement, the member I26 comes into contact with and-raisesthe lever arm I22. Lever arm I22 is76 loosely pivoted upon the shaftI03. and 'a. counterweight I24 is adjustably mounted thereon, tocounteract the pressure above the diaphragm 80 until a predeterminedpressure is reached. The lever arm I22 may be bent at the outer or freeend thereof to form a vertical extension I26 adapted to rest upon thecasing of the chamber 50 under normal conditions.

Attached to the bucket 62 and extending vertically upward through-thetop of the frusto-conical cover 60 is a rod i28 notched at I30 andcarrying at its upper end a collar I32 (Fig. 5). The latch I04 normallyengages the notch I30 and maintains the rod .428 in a raised position.In this position the bucket 62 containing the body of sealing liquid 14,seals off communication between valve chamber 50 and the outeratmosphere thru pipe 56. t

The valve mechanism thus described is intended merely as a safety valve,and hence under normal conditions will remain in the positionillustrated in Fig. 5., However under rapid temperature changes, or forother cause, the pressure within the system may occasionally vary beyondthe pressure limits for which the valve is set. When the pressure withinthe tank I increases, the pressure within the chamber 30 and in thecommunicating compartment 82 of the diaphragm chamber III will increaseaccordingly and tend to lift the. weighted diaphragm 80. Thecounterweight H4 is adjustable on the lever II4 to restrain the upwardmovement of diaphragm 80 until a predetermined limiting pressure hasbeen reached. Whenthls limiting pressure is reached, the diaphragm 30will rise and lift the arm 98 of the double bell crank which is attachedto the shaft I08, and, by means of member II2, will lift the lever arm 4and the counterweight H6, In this movement the arms I00 and I02 of thedouble bell crank will be actuated as shown in Fig. 6, and the latch I04will be disengaged by meansci bar I02 from the notch I30 in the rod I28,allowing the heavier bucket 62 with its retaining rod I23 to fall. Asbucket 62 falls, beams 68 and 33 swing on the bearings 13 and bring thebucket 64 into sealing relationship with the pipe 54, thus sealing of!this outlet pipe and simultaneously opening the chamber 50 to theoutside atmosphere through the pipe 56 and the openings 38.

similarly, when the pressure within the system decreases, the pressurewithin the chamber 50 and the compartment 02 of the diaphragm chamberwill decrease accordingly and the diaphragm 80 will tend to fall. Thecounterweight I24 is adjustable on the lever arm I22 to restrain thedownward movement of diaphragm 30 until a preto lift the lever arm I22and counterweight I24.

In this movement the upper arm of the double bell crank will disengagethe latch I04 from the notch I30 by means of bar I03, allowing thebucket 62 to fall and eflect simultaneous sealing of the pipe 5,4 andthe opening of chamber to to latch I34 (Fig. 6), which is pivotallymounted on a bracket I36 extending upwardly from the cover". The latchI34 is normally held in an approximately horizontal position (Fig. 4) byspring I38 extending from the bracket I36 to the arm I34. Normally latchI34 engages the pin I40 attached to the shaft of the counterweightedflag arm I42 which is held in an approximately horizontal position. Atone end of the flag arm I42 is a flag or other symbol I44 overbalancedat theother end by a weight I46. When the collar I32 trips the latchI34, the signal arm I42 is released and swings to a vertical position sothat the flag may notify the operator that the pressure on the systemhas exceeded the set limits, and has tripped the safety valve, cut thetank ofl of the system, and vented it to the atmosphere.

The safety valve is designed for manual re setting, and may be manuallytripped when it is desired to disconnect an oil storage tank from thesystem.

The invention having been thus described, what is claimed as new is:

1. A fluid storage system comprising a normally sealed oil storage tank,a variable volume gasholder, a breather line communicably connecting thegas space at the top of said tank and said I holder, and a safety valveconnected in said breather line having mechanism operably responsive tovariations of pressure within. said system from a predetermined maximumand a predetermined minimum for simultaneously cutting oil communicationbetween said tank and said holder and breaking the seal between saidtank and atmosphere. t5

2. In a petroleum storage system, a sealed oil ;storage tank havingupright cylindrical walls and the roof of said tank and its bottom curband strengthening the same against press'uresim- 45 pressed thereon bysaid holder lift, and a safety valve having a normally closed reliefconduit incorporated in said breather line to compensate for any lack ofbreathing capacity during periods of abnormal pressure change in saidsystem, said 4 safety valve including mechanism responsive to abnormalpressures within said system operative to break the seal on said reliefconduit and to close said breather line.

3. In a. petroleum storage system, a sealed oil storage tank havingupright cylindrical walls and a conical'roof, a variable volume gasholder of the movable lift type, a vaporbreathing line communicablyconnecting the top of said tank and said holder and forming therewith a.vapor breathing system and reinforcing members connecting pointsintermediate the peak and periphery of thereof of said tank and itsbottom curb and strengthening the same against pressures impressedthereon 'by said holder lift.

4. A reinforced liquid storage tank havingcylindrical walls and aconical roof, the periphery of which is attached to the upper edges ofsaid cylindrical walls-said roof being reinforced by a series of beamsattached thereto intermediate the peak and the periphery thereof, and bytension members connecting said beams and the lower portion of said tankwalls.

5. A reinforced liquid storage tank having cylindrical walls and aconical roof, reinforcing fl iromthepeaktotheperipheryoisaidroonand tierods extending diagonally from pointsintermediatethepeakandperipheryottheroot.to

thebottomq boisaidtank.

8. A reinforced liquid storage tank havingcylindrlcalwalisahdaconicalMOLandreiniorcingiorsaidrooicomprismgaseriesottensionrods of adjustable length extending diagonally from spaced radial pointsintermediate the peak andperiph'ery of said to m me. around the bottomcurb. 7. A liquid s tank walls and a conical root, rigid reinforcingmembers attached to said root termediate the peak and peripherythereof,and a plurality of tension members extending from said-relniorcin'gmembers to pivotalplatesandtrom'saidplatestothebottomcurboisaidtankwalisandtoa-plate centrally located within saidtank.

8.Inapetroleumstoragesystem.asealedoil mtanhavariahlevolumegas mbreathing iine communicablythetopoisaidtankandsaidholderandiormingtherewith a vapor breathing system. a safety-- valvohaving a normallyclosed reliei conduit liquidseal bucket valveavthe heavier of 10 whichis mounted in normal closing relationshipwithsaidreiieiconduitandtheotheroiwhich bucket valves is adapted toclose the normally 'openbreathinglineconnectlngsaidtankand we toabnormal pressures within said system ior actuating said bucket valvessimultaneholder, 'said satety valve including mechanism is responsi-0ilsly-t0break'thesealm1drel1ef00ndiiitand' to close we breather line.

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